A number of cast resinous objects have been produced which employ inert fillers dispersed throughout a thermosetting resin such as polyester. Known filler materials include limestone (calcium carbonate), glass fibers, asbestos, cinders, silicates, metal powders, quartz, clay, sand, alumina, volcanic ash, and the like.
It is common practice to mix several inert fillers with a resin binder to form a product of the desired properties. For example, it is well known that spherical particle shapes may be highly loaded in the binder but that such shapes do not form as strong an adhesive bond as do irregular shaped particles. On the other hand, irregular shaped particles of a generally uniform grade do not pack well and so a greater proportion of binder must be employed.
A composition formed of a polyester binder with calcium carbonate filler has been employed for a variety of synthetic marble products. Among the deficiencies of calcium carbonate filler is the relatively low tensile strength of the final product. Thus the product would have limited industrial application. Furthermore, since calcium carbonate is highly reactive with acid, a surface formed with it as filler may be permanently disfigured by acid contact.
There is a pressing need for sources of economical disposal of the residue of industrial and municipal solid waste treatment such as for recycled glass. Certain extremely fine residues (e.g., less than 50 microns) are particularly difficult to dispose of because, in their impure state, they are not suitable for use in recycled glass. Such fine residues include incinerated waste or coal fly ash and the residue of certain pyrolysis processes.